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GALVANIC PROTECTION OF ANTI-CAVITATION LAYER BY AN UNDERLAYER

IP.com Disclosure Number: IPCOM000026884D
Original Publication Date: 1994-Feb-28
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 113K

Publishing Venue

Xerox Disclosure Journal

Abstract

Thermal ink jet devices typically employ a transducer which operates in a hostile environment of an aqueous solution (ink) at elevated temperatures and under high pressure. The ink is normally a mixture of water, glycols, dyes and additional additives. Very often, these conditions encourage the degradation of the interface between the ink and the transducer through a mechanism known as hydrogen embrittlement. Characteristically, failure caused by hydrogen embrittlement is a delayed process, and is due to formation of a brittle path through the lattice of the transducer material with an accumulation of hydrogen. Many materials are susceptible to hydrogen embrittlement, including glass, ceramics and polymers, however, primary practical implications are most widely known with respect to metals.

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XEROX DISCLOSURE JOURNAL

GALVANIC PROTECTION OF ANTI- CAVITATION LAYER BY AN UNDERLAYER Int. C1. HOlr 4/38 Igal E. Klein
William G. Hawkins

Proposed Classification
U.S. C1.437/255

Thermal ink jet devices typically employ a transducer which operates in a hostile environment of an aqueous solution (ink) at elevated temperatures and under high pressure. The ink is normally a mixture of water, glycols, dyes and additional additives. Very often, these conditions encourage the degradation of the interface between the ink and the transducer through a mechanism known as hydrogen embrittlement. Characteristically, failure caused by hydrogen embrittlement is a delayed process, and is due to formation of a brittle path through the lattice of the transducer material with an accumulation of hydrogen. Many materials are susceptible to hydrogen embrittlement, including glass, ceramics and polymers, however, primary practical implications are most widely known with respect to metals.

Hydrogen embrittlement is a phenomena which is extensively do~urnented.1~2~3 Common control measures are also widely known4, one of which is to couple the metal subject to embrittlement with a more noble metal. This coupling yields a local galvanic cell in which the metal to be protected serves as an anode, thus deterring permeation of the hydrogen ions into the metal lattice. Other embrittlement inhibition methods include applying an external biasing potential, adding inhibitors to the environment, and providing a protective coating.

In thermal ink jet transducers, the most severe conditions are experienced by the anti-cavitation layer. Functional failure of the printhead is evident when the layer breaks off locally. Fortunately, any extra protection to the anti- cavitation layer will result in prolonged lifetime of the transdu...